Screws and other threaded fasteners are known to be driven by tools engaging a recess in a head of the fastener. A simple drive configuration for the head of a fastener is a slot across the head for receiving the blade of a screwdriver. Other drive configurations are also known, including substantially closed recesses in the head of the fastener, such as recesses designed to receive driving tools having complementary six lobed outer surfaces. Confined drive configurations are advantageous in providing a more positive engagement of the driver within the drive configuration than is provided by a more open drive configuration and the driver associated with it.
It is known to plate or coat screws and other fasteners with different types of finishes for various purposes, both functional and aesthetic. Some of the finish materials are generally thick and heavy, and have a tendency to clog or fill the recesses required by six lobe drive bits used to drive the fasteners into holes, clips or bosses. Plating materials are used to protect screws from rusting or corroding over time due to exposure to salt, water, abrasive solvents or other undesirable elements. Plating materials are used also to provide a desired color, or to make a fastener of steel or other more durable and/or less expensive material appear as if it is gold, silver, brass or other less durable and/or more expensive material.
So called “plated” fasteners can be provided with plating of various types applied in different processes. In a known, basic plating process, screws or other fasteners are held in a bin or basket, which is then submerged in a plating bath. Various techniques can be used to perform the plating or coating process, such as electroplating. Immersion processes for applying coatings also are known. After immersion, the bin or basket is removed from the plating or coating bath, and the fasteners are subjected to a spinning process intended to remove excess material from the internal drive feature of the screw head. However, it is not uncommon that some of the plating or coating material will remain in the drive configuration recess, particularly if a substantially closed configuration is provided, such as the aforementioned six lobe drive configuration.
Excess plating or coating material retained in a drive configuration recess can harden and make insertion of drive tools difficult. This can adversely affect manufacturing and assembly processes that require rapid, consistent fastener engagement. In some plating or coating processes, the scrap rate from fasteners having excess material in the drive configuration recesses can be quite high. Many times the rejected fasteners are otherwise acceptable and suitable, except for the accumulation and hardening of excess plating or coating material in the drive configuration recess. High rejection rates are wasteful.
What is needed is a drive configuration for the heads of fasteners that promotes clearing of plating or coating material from the drive configuration recess during the plating or coating process.